The Internet has swept into the American vocabulary and spawned so many new words - netizen, chat room and home page, to name a few - that it has come to represent a time in the nation's social history, says Mr. Morse.

Just a century ago, another form of communication swept into the language. In the 1898 edition of Merriam-Webster's Collegiate Dictionary, the hot new word was telephone. Telephone helped spawn a wide range of new words and phrases - busy signals, wrong numbers, voice mail, cell phones. It also gave America its standard greeting: hello.

But Internet is holding its own, in part by borrowing words from an older technology and giving them new meaning, such as bookmark, address, copy, and browser. "That's how the vocabulary evolves," Morse says. "It's human nature to make the concepts easier to understand by using a familiar, in this case print-based, metaphor."

Allan Metcalf, a professor at MacMurray College in Jacksonville, Ill., helps put together a list of words of the year for the American Dialect Society. He says the word Internet is a strong candidate to define the end of the century, but he has another preference: words with the prefix e-, as in e-mail or e-commerce.

"It has a little more punch, and it goes beyond the thing to convey the attitudes and a mindset," Metcalf says. He also likes the word teenager, which came into use in the 1930s.

At Merriam, new words earn a place in the dictionary simply by repeated use in the popular press. Merriam's lexicographers spend a large part of their day reading newspapers, magazines - and now Internet publications. Each new word and usage - along with a clipping from the publication showing how it was used - goes into an electronic database.

A new word must amass enough citations to indicate its acceptance by the American people before it goes into the dictionary. "We are constantly charging and renewing our language and that is why it is so robust," Morse says.